In his research Simon Le Vay analysed the hypothalamus of dead people – male, female, homosexual and heterosexual.

In 1991, Le Vay published “A difference in hypothalamic structure between heterosexual and homosexual men” in Science. The study reported that the hypothalamus of homosexual and heterosexual men were different. However the data was not conclusive. Regardless, the media often reported he had found a genetic cause of homosexuality. In 1994, in an article in Discover Magazine, Le Vay cautioned about misinterpreting his work. He wrote “It’s important to stress what I didn’t find. I did not prove that homosexuality is genetic or find a genetic cause for being gay. I didn’t show that gay men are born that way, the most common mistake people make in interpreting my work. Nor did I locate a gay center in the brain.”